Propeller



Oct. 20, 1942. A. ROBER 2,299,592

PROPELLER Filed Sept. 3, 1940 2 Sheeis-Sheet 1 A. ROBER PROPELLER Oct. 20, 1942.

Filed Sept. 3, 1940 2 Sheets-Sheet 2 a nz onfzder ATTOR N EYS mama Oct'. 20, 1942 UNITED STATES PATENT OFFICE P5332 1 Anton Bober, Milwaukee, Wis. Application September 3, 1940, Serial No. 355,267

1 Claim. (Cl. 170-172) My invention relates to new and useful improvements in airplane propellers.

An important object of my invention'is to provide an airplane propeller that has provision for the passage of a fluid medium longitudinally therethrough. The said propeller being powerdriven and the centrifugal force created thereby acting as a means for drawing atmospheric air therethrough.

Another object of my invention is the provision of a propeller of the above-mentioned character wherein the outer outlet ends of the internal air passages are uniquely shaped to utilize the discharging air in a manner whereby the blades of the propeller may better obtain traction against the air through which they are moving.

Still another object of my invention is the provision of a propeller of the above-mentioned character that is simple in its construction and that is eflicient and eillcacious in the performance of its duties. 7

Other objects and advantages of my invention, will be apparent during the course of the following description.

In the drawings, forming a part of this specification, and wherein like numerals are employed to designate like parts throughout the same,

Figure 1 is a top plan view of a propeller assembly embodying my invention,

Figure 2 is a front elevation thereof,

Figure 3 is a fragmentary rear elevation illustrating the construction of the hub and showing the association of the shanks of the propeller blades therewith,

V Figure 4 is a vertical sectional view taken on the line 4-4 of Figure 3,

Figure 5 is a fragmentary transverse sectional view taken on the line 5-5 of Figure 3,

Figure 6 is a transverse sectional view taken on the line 6-6 of Figure 7 and illustrating a propeller blade constructed in accordance with the present invention,

Figure 11 is a fragmentary bottom plan view of another modification of my propeller blade,

Figure 12 is a transverse sectional view taken on the line l2-lz of Figure 11, and Figure 13 is a transverse sectional view of modined lOlm of the propeller shank.

propeller It is fixedly mounted thereon.

Figured-a is a transverse sectional view showing a modification of Figure 6,

Figure 7 is a longitudinal sectional view of my propeller blade taken on the line 1-1 of Figure 6, Figure 8 is a plan view of the locking disk adapted to hold the blades of the propeller in fixed association with the hub,

Figure 9 is a fragmentary perspective view further illustrating the association of the propeller shanks with the hub,

Figure 10 is a transverse sectional view of a modified form of my propeller blade.

My invention concerns itself principally nth the shape and construction of the propeller carried by the shaft 15, whichpropeller includes a central hub portion H and radially extending blades 18. The blades are here illustrated as being two in number and as being disposed in diametrically opposed relation with each other; however, it is to be understood that any number of blades desired may be used and that the present number is shown merely for the purpose of illustrating the invention. p

The hub comprises a base ring casting l9 and a cap 20 which are detachably connected to each other, in a. manner whereby the outside surfaces thereof join smoothly to provide an essentially conical-shaped unit. outer annular shell 2| and a central bearing 22 connected by the radially extending bifurcations 23 and 24. The outer end of each of the bifurcations terminates within the shell so that the internally splined sleeves 25 and formed at their ends may receive the externally splined butt ends of the'propeller shanks. As shown at Figure 3, each of the sleeves 25 is disposed to project through the exterior portion of the shell casting It so that the bores of the sleeves extend tangentially through the casting. The inner sleeve 28 of each pair of sleeves aligns with the outer sleeve to radially position the longitudinal axis of its respective propeller blade in the manner illustrated in Figure 2. The bearing :2 is splined to the extending end of the crankshaft it the tip of which shaft is screw-threaded, as at H, to

vent the nut from being inadvertently unthreaded from the crankshaft. Obviously, tightening of the nut upon the threaded end of the shatt The casting comprises an will cause the tapered inner end thereof to press snugly against the seat as in a manner to hold the bearing fixedly and permanently attached to the shaft.

The base of the hub cap 2d is provided with construction and each is identically associated or connected to the hub. A. detailed description. of but one of the blades will, therefore, be given.

The bladelli is provided with an elongated shank the inner end 36 of which is tapered and received within the sleeves it and 2a and the outer end of which is flattened, as at 3?. The inner tapered end 36 extends to substantially the rearward face it of the sleeve it and is fixedby held therein by means of the locking disk 39. The disk is provided with a circumferential wedge-shaped portion at extending from one side thereof which fits within the flared recess M in the rearward side of the sleeve. The inner periphery of the disk is formed at right-singularly disposed diametrically opposed sides thereof with spaced pairs of lugs 52 which extend at opposite sides of the openings at in the end of the propeller shank. The bolts it pass between the pairs of tabs and into the openings 53 and tightening of the bolts will operate to pull the tapered end of the shank into pressed engagement with the sleeves.

The flattened end portion 3? of the blade comprises an integral part of the shank and in the form thereof illustrated generally. in Figures 1 to 9, and specifically in Figures 6, 6a and 7 it comprises three spaced parallel fins id, at and al. The outer ends of the fins are closed by a vertical wall 48 to provide elongated slots or passages #39 which extend the full length of the blade and open through the leading edge 56 and trailing edge thereof. The hub cap is provided with a plurality of circumferentially spaced perforations 52 and the propeller shank is provided with a longitudinally extending passage 53, which passage discharges air entering through the perforations into the passages 55', 5d and 55 in the fins 45, t8 and M. From the passages within the fins the air is discharged into the passages as intermediate the fins through a plurality of outlet ports be adjacent the leading edges thereof. The outlet ports 55 in the two lowermost fins 6G and ll open through the upper surfaces thereof and into the passages d9, whereby air entering the said last-mentioned passages will traverse the same for substantially their entire width. The outlet ports in the upperrnost fin 55 open through-the bottom surface thereof and into the uppermost passage 49 for reasons presently to be made apparent.

As best illustrated in Figure 6, the leading edges of the fins are beveled, as at 51, and the trailing edges thereof are beveled, as at 58. In addition to the beveled formation 58, the trailing edge of each of the fins is bent 'angularly downwardly to provide striking surfaces 59 against which the air traversing the passages 449 will be impinged. The angularly bent rearward edges of the fins may be either plane or curved, the

plane construction being illustrated in Figure 6 and the curved construction in Figure 6-a. Air traversing the upper passage 39 will be impinged against the obliquely disposed trailing edge of the upper fin it and air traversing the lower passage 69 will be impinged against the obliquely disposed striking face of the rim as. If desired, suitable supporting braces bit may be disposed between the'fins at spaced intervals throughout the length of the blade to support and strengthen the same.

When the propeller is being rapidly rotated the air "in advance of the propeller is drawn therein and, by reason of the unique shape of the propeller blades, is hurled rearwardly thereof at a greatly accelerated velocity. situation causes a condition or reduced atmos pherie pressure to exist slightly in front of the blades and a condition of increased atmospheric pressure to exist rearwardly thereof. The utility of a propellendepends to no small extent on the traction which it may obtain on the air in that the propeller literally screws itself through the air. The present arrangement, therefore, contemplates a propeller construction adapted to increase the traction which the blades of the propeller may obtain. As hereinbefore described, rotation of the propeller will cause air to pass through'the slots 59 between the fins at the ends of the blades. The air traversing the slots will flow by the outlet ports 53 and tend to pull or exhaust the air from the passages 53, and 555.

p The semi-exhausted condition of these passages will cause air to be-sucked into the perforated propeller hub and along the shank-and fin passages, which last-mentioned flow is discharged .through the ports to augment the air already flowing therethrough. The increased pressure against the oblique striking faces 59 at the trailing edge of the fins will give the blades greater tractive force and will materially increase the efiiciency-of the propeller.

Each of the blades is preferably inclined from the horizontal at substantially the angle illustrated in Figure 6; however, this angle may be readily adjusted to suit the exigencies of the particular situation. The periphery of the shank 35 adjacent the outwardly extending end of the sleeve 25 is provided with circumferentially spaced marks 6i which cooperate with the arrow 62. on the edge of the sleeve to indicate the relative angular position of the fins at the end of the blade. If the bolts i l are-disengaged from the butt ends of the propeller shanks, the said shanks may be removed from the sleeves and reinserted at the desired angle, the angle being accurately ascertained by the particular mark M in register with the arrow 62. Reinsertion of the bolts 5% will then force the annular wedge d2 of the disk into the recess ii to thereafter eificaciously hold the shank against longitudinal displacement.

It is to be understood that the number of fins which may be used is not restricted to any particular number and that three fins are illustrated in Figures 1 to 9 merely for the purpose of illustration. Figure 10 shows a propeller blade construction which embodies two fins 63 and er. The outer ends of the fins are closed in the manner described for the preceding form and the slot or passage 65 opens through the leading and trailing edges of the blade. The construction of the blades and the formation of the fins is substantially identical with the form hereinbefore described. Both of the fins 53 and 64 are provided with longitudinal passages 65,

This unique The passages 66 communicate with the longitudinal passage of the shank to deliver air through the outlet port 61 and into the passage ll intermediate thevfins in the same manner hereinabove described for the first form of the invention. The further construction and mode of. operation of this form of the invention is so similar to the form hereinabove described that no further explanation is thought to be necessary,

I Figures 11 and 12 illustrate a construction wherein only one fin 6| is required. The fin is integrally connected with the distal end of the shank and the leading edge thereof is beveled, as at 69, and the trailing edge thereof is beveled, as at 10. The trailing edge of the fin is similarly bent angularly downwardly to provide a striking surface-12 against which air is impinged in the manner hereinbeioredescribed. The fin is provided with a longitudinally extending passage 13 and the bottom face H of the fin is provided at spaced intervals along its length with an outlet port. The sides the ports confronting the trailing edge of the tin are bent inwardly to provide the tabs Il'which extend slightly into the passage 13. drawn from the shank passage and into the passage 13 will be directed by the concave outer surfaces of the tabs along the face II of the fin and against the striking surface of the trailing edge. Itis preferred that all of the parts which open through the bottom faces of the fins be formed in the manner first described and as. lllustrated in the drawings.

' Figure 13 is a cross-sectional view of a modification ot the propeller shank. The internal passage 53- thereof is divided by rum angularly The air disposed supporting partition walls I! which d v 3 substantially increase the strength and durability of the blade. The outer endsof the subpassages 16 formed by the partition walls may open into a common chamber for discharging the air into the hollow fins or if a plurality of the fins are used, certain of the fins may be individually connected to corresponding subpassages.

It is to be understood that the form of my invention, herewith shown and described, is-to be taken as a preferred-example of the same, and that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of my invention. or scope of the appended claim.

Having thus described my invention, I claim: 7 A propeller assembly comprising a hollow perforated hub, and radially extending blades having tubular shank portions connected to and communicating with the hub and blades provided at the distal ends of the shanks, which blades comprise spaced parallel fins extending in or parallel to a plane containing the blades so that the passages therebetween extend the full length of theblade and open through both the leading and trailing edges thereof, each of the fins being angularly oflset at its trailing edge to provide an oblique striking surface for air pass- ,ing through the passagesand angularly offset at its meeting edge to direct the air against the said striking surfaces, certain of said flns being hollow and receiving a current of air from the internal bores of the shanks and discharging the same through outlet ports and intothe passages between the finsin a manner to augment the now of air through the said passages.

. ANTON ROBER. 

